Ordinarily, coating or vapor deposition reactors are employed as a processing chamber, for example, in semiconductor technology, for coating wafers or other semiconductor structures and other substrates. The substrates, e.g., wafers may be placed in an inner receptacle, and a suitable pressure for the process to follow is produced by a vacuum pump connected to the processing chamber. The inner receptacle surrounds a reaction space.
As soon as, after introduction of the materials or substrates to be processed, the requisite pressure required in each instance for the particular coating or vapor deposition process has been reached in the inner receptacle, the process in question is started.
After processing of the substrates in the inner receptacle, the normal ambient pressure is established in the latter, so that it may be opened and the processed substrate removed.
In the processes described, which are carried out in vacuum systems having so-called inner receptacles in which the actual material or substrate to be processed is located, process control represents a considerable problem.
The inner receptacles are, for example, required if the reactor chamber must be protected from the actual reaction in the reaction space in the inner receptacle, or vice versa.
If the separation also requires a ‘gas-technical’ shielding, necessarily different pressure conditions will establish themselves. In such a case, a pressure measurement and hence a targeted process control, for example, by the action of temperature, is not possible. The reason for this lies in that the installation of a pressure measuring tube in the inner receptacle is generally not possible because of an undesirable interaction between the process and conventional pressure pick-ups, or if the inner receptacle must be transported together with the substrates inside the processing chamber.
Consideration is now being given to the design and configuration of pressure measuring device for vacuum systems that are used for the surface coating or modification of objects and/or substrates. Attention is in particular, to the measurement of pressure in vacuum systems in which processing of substrates in conducted in an inner receptacle, which defines a reaction space, inside an outer processing chamber. Desirable pressure measurement devices, will provide a continuous and secure determination of the pressure in the internal receptacle and/or the pressure difference between the inner receptacle and the outer processing chamber.